如何从多个 MySQL 表中提取数据

Question

I am making these three MySQL queries consecutively to pull the information I need, then I combine them in excel. Although, I believe there is a better way to make one single query and get all the information at once. I am totally lost with JOIN statements, so could anyone please help me to construct the query I am looking for?

All I am trying to pull is the field "inventory_cost.cost".

SELECT 
    sku,
    UCASE(metal),
    SUM(ABS(qty+s5qty+s6qty+s7qty+s8qty+s9qty+s10qty+s11qty+s12qty+s13qty)) AS qtySold 
    FROM inventory_history
    WHERE reason = "order"  
    GROUP BY sku,metal 
    ORDER BY sku,metal ASC


SELECT sku,UCASE(metal),id FROM inventory GROUP BY sku,metal ORDER BY sku,metal ASC

SELECT inv_id,cost FROM inventory_cost ORDER BY inv_id

All your help is most appreciated!!

Burcin

Answer 1

SELECT sku, UCASE(metal), 
SUM(ABS(qty+s5qty+s6qty+s7qty+s8qty+s9qty+s10qty+s11qty+s12qty+s13qty)) AS 
qtySold 
,cost = ic.cost * 
SUM(ABS(qty+s5qty+s6qty+s7qty+s8qty+s9qty+s10qty+s11qty+s12qty+s13qty))
FROM inventory_history ih join inventory inv on inv.sku=ih.sku
join inventory_cost ic on ic.inv_id=inv.id
WHERE reason = "order"
GROUP BY sku,metal
ORDER BY sku,metal ASC

Let me know if you have any more queries.